A new breakdown failure mechanism in HfO2 gate dielectric

The breakdown failure mechanism in HfO₂ high-k gate dielectrics under constant voltage stress in inversion and accumulation mode is physically analyzed with the aid of high resolution transmission electron microscopy. The results show that the breakdown phenomenon in HfO₂ gate dielectrics is different from that of ultrathin SiO_xN_y and Si₃N₄ gate dielectrics. Dielectric-breakdown-induced epitaxy, which is the failure defect responsible for breakdown in SiO_xN_y and Si₃N₄, has also been observed in HfO₂ but in a slightly different morphology. The microstructural damages observed in the breakdown of HfO₂ gate dielectrics are probably related to HfSi_x and HfSiO_x formation during BD event.